diff --git a/src/main/java/de/bixilon/minosoft/data/world/positions/BlockPositionUtil.kt b/src/main/java/de/bixilon/minosoft/data/world/positions/BlockPositionUtil.kt
index 60ff01797..6d07def1a 100644
--- a/src/main/java/de/bixilon/minosoft/data/world/positions/BlockPositionUtil.kt
+++ b/src/main/java/de/bixilon/minosoft/data/world/positions/BlockPositionUtil.kt
@@ -24,6 +24,10 @@ object BlockPositionUtil {
         return hash shr 16
     }
 
+    inline fun assertPosition(condition: Boolean, message: String) {
+        if (!DebugOptions.VERIFY_COORDINATES) return
+        if (!condition) throw AssertionError("Position assert failed: $message")
+    }
     inline fun assertPosition(condition: Boolean) {
         if (!DebugOptions.VERIFY_COORDINATES) return
         if (!condition) throw AssertionError("Position assert failed!")
diff --git a/src/main/java/de/bixilon/minosoft/data/world/positions/InSectionPosition.kt b/src/main/java/de/bixilon/minosoft/data/world/positions/InSectionPosition.kt
index db6ce1f92..4441e5b04 100644
--- a/src/main/java/de/bixilon/minosoft/data/world/positions/InSectionPosition.kt
+++ b/src/main/java/de/bixilon/minosoft/data/world/positions/InSectionPosition.kt
@@ -40,7 +40,7 @@ value class InSectionPosition(
 
 
     inline fun plusX(): InSectionPosition {
-        assertPosition(this.x < ProtocolDefinition.SECTION_MAX_X)
+        assertPosition(this.x < ProtocolDefinition.SECTION_MAX_X, "x < max")
         return InSectionPosition(index + X * 1)
     }
 
@@ -50,12 +50,12 @@ value class InSectionPosition(
     }
 
     inline fun minusX(): InSectionPosition {
-        assertPosition(this.x > 0)
+        assertPosition(this.x > 0, "x > 0")
         return InSectionPosition(index - X * 1)
     }
 
     inline fun plusY(): InSectionPosition {
-        assertPosition(this.y < ProtocolDefinition.SECTION_MAX_Y)
+        assertPosition(this.y < ProtocolDefinition.SECTION_MAX_Y, "y < max")
         return InSectionPosition(index + Y * 1)
     }
 
@@ -65,12 +65,12 @@ value class InSectionPosition(
     }
 
     inline fun minusY(): InSectionPosition {
-        assertPosition(this.y > 0)
+        assertPosition(this.y > 0, "y > 0")
         return InSectionPosition(index - Y * 1)
     }
 
     inline fun plusZ(): InSectionPosition {
-        assertPosition(this.z < ProtocolDefinition.SECTION_MAX_Z)
+        assertPosition(this.z < ProtocolDefinition.SECTION_MAX_Z, "z < max")
         return InSectionPosition(index + Z * 1)
     }
 
@@ -80,7 +80,7 @@ value class InSectionPosition(
     }
 
     inline fun minusZ(): InSectionPosition {
-        assertPosition(this.z > 0)
+        assertPosition(this.z > 0, "z > 0")
         return InSectionPosition(index - Z * 1)
     }
 
diff --git a/src/main/java/de/bixilon/minosoft/gui/rendering/light/ao/AmbientOcclusionUtil.kt b/src/main/java/de/bixilon/minosoft/gui/rendering/light/ao/AmbientOcclusionUtil.kt
index 5c9ac2f80..1920738c3 100644
--- a/src/main/java/de/bixilon/minosoft/gui/rendering/light/ao/AmbientOcclusionUtil.kt
+++ b/src/main/java/de/bixilon/minosoft/gui/rendering/light/ao/AmbientOcclusionUtil.kt
@@ -33,7 +33,7 @@ object AmbientOcclusionUtil {
 
     val EMPTY = IntArray(LEVELS) { LEVEL_NONE }
 
-    fun ChunkSection?.trace(x: Int, y: Int, z: Int): Int {
+    fun ChunkSection?.trace(x: Int, y: Int, z: Int): Int { // TODO: use packed and direction
         if (this == null) return 0
         var x = x
         var y = y
@@ -163,7 +163,7 @@ object AmbientOcclusionUtil {
     }
 
     fun applyWest(section: ChunkSection, position: InSectionPosition, ao: IntArray): IntArray {
-        if (position.z == 0) {
+        if (position.x == 0) {
             return setX(section.neighbours?.get(O_WEST), position.with(x = ProtocolDefinition.SECTION_MAX_X), true, ao)
         } else {
             return setX(section, position.minusX(), false, ao)
@@ -171,7 +171,7 @@ object AmbientOcclusionUtil {
     }
 
     fun applyEast(section: ChunkSection, position: InSectionPosition, ao: IntArray): IntArray {
-        if (position.z == ProtocolDefinition.SECTION_MAX_X) {
+        if (position.x == ProtocolDefinition.SECTION_MAX_X) {
             return setX(section.neighbours?.get(O_EAST), position.with(x = 0), true, ao)
         } else {
             return setX(section, position.plusX(), true, ao)
diff --git a/src/main/java/de/bixilon/minosoft/gui/rendering/sky/clouds/CloudLayer.kt b/src/main/java/de/bixilon/minosoft/gui/rendering/sky/clouds/CloudLayer.kt
index 59657ae18..e4f139bfa 100644
--- a/src/main/java/de/bixilon/minosoft/gui/rendering/sky/clouds/CloudLayer.kt
+++ b/src/main/java/de/bixilon/minosoft/gui/rendering/sky/clouds/CloudLayer.kt
@@ -28,7 +28,7 @@ class CloudLayer(
     val index: Int,
     var height: IntRange,
 ) {
-    private var position = ChunkPosition(Int.MIN_VALUE, Int.MIN_VALUE)
+    private var position = ChunkPosition(-ChunkPosition.MAX_X, -ChunkPosition.MAX_Z)
     private val arrays: Array<CloudArray> = arrayOfNulls<CloudArray?>(3 * 3).unsafeCast()
     private var offset = 0.0f
     var movement = true